In rotary piston mechanisms of the trochoidal type having a multi-lobed housing cavity defined by two housing walls spaced apart by a trochoidal shaped peripheral wall and within which a multi-cornered rotor is eccentrically supported for planetary movement, it is well known to employ a rotor having cavities between the hub and flank portions which cavities communicate exteriorly of the rotor through openings in the faces of the rotor and to cool the rotor by spraying liquid utilized for lubricating the shaft and rotor bearings into the rotor cavities. Such a rotary mechanism is exemplified in the U.S. patent to Bentele et al., U.S. Pat. No. 3,176,915, wherein a nozzle is carried in the eccentric portion of the drive shaft and in communication with a lubricant supply channel to direct lubricant into the rotor cavities to effect cooling of the rotor. Since the nozzle is constantly open, lubricant is sprayed into the rotor regardless of the operating temperatures of the mechanism. This functional condition retards the rapid rise of the mechanism to the desired operating temperature and results in high fuel consumption. Furthermore, because cooling liquid (lubricant) is continuously emitted by the nozzle into the cavities of the rotor, it is possible, at low speeds and idling conditions, to cause a build-up of a high, detrimental pressure of the liquid lubricant so that inadequate lubrication of the shaft and rotor bearings may occur.
One suggested solution to the aforementioned problems is exemplified in Japanese Pat. No. 47-14481 wherein the lubricant supply to the cooling nozzle is regulated by a thermostatically controlled valve in the rotor. The valve is a pivotal bushing which closes or opens the supply passage to the nozzle under the urging of a thermostat. It has been found that such an installation is not reliable because it is mounted in the rotor and is, therefore, subjected to centrifugal stresses. Moreover, the function of the thermostatically controlled valve is not observable and to effect repairs to the device would necessitate extensive and expensive disassembly and assembly work. The present invention, therefore, seeks to avoid the aforementioned disadvantages of presently known rotor cooling systems of the type utilizing liquid lubricant as a coolant.
Accordingly, one object of the present invention is to provide an improved rotor cooling system employing liquid lubricant which is capable of regulation in accordance with load, operating temperature and coolant pressure.
It is another object of this invention to provide an improved rotor cooling system employing liquid lubricant which is readily accessible for inspection and repair.
A further object of this invention is to provide an improved rotor cooling system employing lubricant as a coolant that has operating reliability.